Original Article
Speed of word retrieval in multiple sclerosis
Ahmad Reza Khatoonabadi, Vahid Shaygan Nejad1, Hooshang dadgar, Fereshteh Ashtari1, Majid Ghasemi1,
Department of Speech‑Therapy, Faculty of Rehabilitation, Tehran University of Medical Sciences, Tehran, 1Department of Neurology,
Faculty of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran
Background: Multiple sclerosis (MS) is a common inflammatory ‑ degenerative disease of myelin sheet of central nervous system that
affects more young people. These patients show some degrees of cognition problems such as memory and processing disorders. The
aim of this study was to evaluate the speed processing ability by word finding assessment in three categories include fruits, animals
and objects in MS patients. Materials and Methods: This study carried out as case‑control and descriptive‑analytic on 47 MS
patients and 29 healthy controls. We measured the reaction time (RT) in three stages. Each stage includes 25 words (animals, fruits
and objects words with high familiarity) that were presented randomly. In each stage, the subject should press a key when recognized
the target category. Collected data analyzed with repeated measure ANOVA, two‑way ANOVA test, and independent‑samples t‑test.
Results: MS patients in comparison to normal healthy subjects show delay in speed of processing in which there was significant
difference between MS patients and control subjects in mean reaction time in all three categories (P < 0.001). Conclusion: The speed
of processing is impaired in MS patients. Consequently, more evaluation and planning treatment programs based of speed processing
for memory in these patients are necessary for them because of the role of memory in daily activities of life.
Key words: Multiple sclerosis, speed of processing, word retrieval
INTRODUCTION
Multiple sclerosis (MS) is a common inflammatory ‑
degenerative disease of myelin sheet of CNS and is
one of the most common disabling diseases among
young adults. According to the existing statistics, MS
is one of the most costly diseases in the United States.
Studies show that patients who suffer from MS has
some levels of cognitive disorder (45‑65%), including
memory disorder, speaking problems, information
process delay, lack of reasoning ability, abstract
thinking, attention and functioning. One of the factors
that faces problem in MS patients is memory and
especially concept memory, which has a bad effect on
patients’ lives. Although there are several studies on
memory of these patients, there is no agreement in the
existing ideas.[1‑9]
Elsass and Zeeberg (1983), Rao et al., (1989) and Kujala
et al., (1994) studied concept memory of MS patients and
reported slow speed of information process.[6‑10] Other
studies on the speed of information processing have
reported deficiency in concept memory as one of the
most significant cognitive disorder in these patients.[11‑13]
In general, the results of many studies prove the
existence of a range of concept memory problems
and concept categorization in MS patients.[11‑13] High
prevalence of MS in IRAN and impairment of memory
in MS patients, and with regard to the role of memory
in relation with daily functioning, the present study
aimed to investigate the ability of word retrieval using
speed processing assessment in three conceptual areas
in MS patients. These areas included fruits, animals
and objects.
MATERIALS AND METHODS
This is a case‑control study analyzing 47 MS patients
who had a mild (3 or less) disability according to the
Expanded Disability Status Scale (EDSS). MS patients
who were selected had relapsing remitting MS and
had an age range of 20 to 50 years. Patients’ conditions
included no relapse at least one month before entering
the study, having no psychological and neurologic
disease apart from MS, lack of language disorder history,
no drug dependency or alcoholism and assuring that
they had no movement disorder in upper organs and
severe lack of sight due to MS.
Sampling was done by random numbers among those
referring to special clinics of neurology, which had the
entry criteria. Patients with mild relapse during the
study were excluded. Twenty nine healthy people were
selected as controls from clinic or hospital’s employees
and other referrer people. All participants were
informed that the tests have no risk and filled a written
consent. Both groups were matched in gender, age and
education level. This study was conducted in clinics and
hospitals of university for four months in 2010.
Testing method
Address for correspondence: Dr. Vahid Shaygannejad, Department of Neurology, Faculty of Medicine, Isfahan University of Medical Sciences,
Isfahan, Iran. E‑mail: [email protected]
Received: 01‑12‑2011; Revised: 23‑03‑2012; Accepted: 12‑02‑2013
| April 2013 |
Journal of Research in Medical Sciences
274
Khatoonabadi, et al.: Word retrieval in MS
Data were analyzed using SPSS with repeated measure
ANOVA, two‑way ANOVA, and independent‑samples t‑test.
RESULTS
In general, MS patients showed delay in replying in all
3 stages as compared with controls [Figure 1].
Descriptive statistics are presented for both groups
separately in Table 1. In order to investigation interaction
effect stimulus*group, repeated measure ANOVA was
performed [Table 2]. We made two‑way ANOVA [Table 3]
to investigation of effect of RT and CR in each group and
finally independent‑samples t‑test [Table 4] was performed
to measure difference between each type of stimulus
between two groups.
According to repeated measure analysis, there was a
significant difference between both groups and stimuli.
There isn’t any significant difference between RT of stimuli in
MS patients, while processing of correct responses is intact.
It indicates that MS affects speed of processing of stimuli.
There is significant difference between two groups for all
stimuli.
DISCUSSION
I n t h i s s t u d y, t h e s p e e d o f wo r d s ’ c o n c e p t u a l
processing (response reaction and accuracy) in three areas
of fruits, animals and objects were assessed. The results
show that MS patients are slow in speed processing in all
three areas as compared to healthy people. These findings
are in agreement with other studies that present cognitive
disorder in MS patients.[6,7,10,13,14]
According to the present study, these patients similar to
controls show a delay in the speed processing of objects
275
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The subject was placed in a room without any distracting
factor (no audio and visual distraction) in front of a monitor
with 30 cm distance. The test was based on reaction time
assessment and was conducted in 3 stages. In each stage,
25 words (including animals, fruits and objects that were
familiar for everybody) were randomly presented. The
laps between stages was 10 seconds and the duration of
presentation of each word was 1000 ms and the laps between
presentation of two words was 2000 ms. In the first stage that
was aimed to recognize animals’ names from the presented
words, the subject should press first key whenever seeing
an animal’s name and press second key if not. The second
and third stages (recognizing names of fruits and objects)
were also conducted as the same.
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Figure 1: Comparison delay in replying in different stages of MS and control
group
Table 1: Descriptive data for both groups
Mean
RT
Object
Animal
Fruit
P value
CR
Object
Animal
Fruit
P value
P value
MS
Control
778.3±81.5
733±80
751.5±82.2
661.1±70.3
602.2±59.8
617.3±78.5
<0.001
8.7±1.2
9.6±0.57
9.1±0.88
<0.001
<0.001
8.7±1.2
8.5±1.6
8.3±9.1
<0.001
MS=Multiple sclerosis; RT=Reaction time; CR=Correct responses
Table 2: Two-way ANOVA
RT
MS
Control
CR
F
P-value
0.775
0.463
8.101
<.001
MS
14.560
<.001
Control
12.051
<.001
Table 3: Independent‑samples t‑test
t
P value
7.043
8.775
7.918
<0.001
<0.001
<0.001
-5.456
-4.537
-3.317
<0.001
<0.001
<0.001
Stimulus
RT
Object
Animal
Fruit
CR
Object
Animal
Fruit
RT=Reaction time; CR=Correct responses
as compared with the two other areas (fruits and animals).
According to the existing theories in this field one of the
reasons for this delay is the wide range of this area as
compared with other areas. The results of studies on the
Journal of Research in Medical Sciences
| April 2013 |
Khatoonabadi, et al.: Word retrieval in MS
reaction time of MS patients show that these patients as
compared to healthy people have delay in reaction times.[6,12]
The study by Rao et al., (1989) on MS patients showed a
delay in the mental processing of these patients.[7‑9] Kujala
et al., (1994) in their studies on MS patients found that the
speed processing in all cognitive areas especially memory
has problem in these patients.[10] Also Patty and Ebers (1998)
in a study reported that one of the most significant disorders
that follow MS is the delay in information processing speed
and conceptual memory.[11] Demaree et al., (1999) in a study
used visual and audio tests on MS patients as compared
with healthy people and found that patients show delay
in the speed processing in both tests. However, when they
were given sufficient time, they acted like healthy people.[13]
Lock (1997) in a test for the retrieval speed of words that
start with specific alphabet found that processing speed of
MS patients had no difference with that of healthy people.
He said that lack of difference in his study was related
to small number of subjects.[14] In other studies also the
deficit of speed processing was mentioned as the primary
problem of MS patients.[15] In a study by Archibald et al. in
2004, it was found that posterior fossa area lesions can lead
to reduced cognitive speed processing and memory in MS
patients.[16,17,18] The findings of the present study also showed
a delay in the speed processing of conceptual areas in MS
patients, which was in agreement with other studies in this
field. Therefore, it can be concluded from the results of this
study and other similar studies that the speed processing
which is somehow the active memory, is disturbed in MS
patients and that memory disorder is related to the daily
functioning of these patients. Therefore, more studies of the
subject and developing proper treatments seem necessary.
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How to cite this article: Khatoonabadi AR, Nejad VS, dadgar H, Ashtari F,
Ghasemi M, Hosseini SK. Speed of word retrieval in multiple sclerosis. J Res
Med Sci 2013;18:274-6.
Source of Support: Nil, Conflict of Interest: None declared.
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